Format: all children stayed in classroom for a normal lesson, and principal from the primary session came and observe. my girl said the principal did asked some questions, my girl raised her hand and was not chosen to answer.
I guess the interview to be held on early K3 just the normal procedure. The criteria for acceptance just based on the performance and appraisal of K1 & K2. :)
According to your description, it is not group interview but just an observation of a normal lesson and the Principal chip in to ask several questions. Is it right?